The present invention relates to a peeling machine. More particularly this invention concerns a downstream guide for such a machine.
As described in European patent document 0,462,322 of Glomb et al, a peeling machine for stripping mill scale and the like from a rod which may be tubular comprises an upstream guide, a central rotary scraper, a downstream guide, and a feeder for advancing the rod along its axis through the guides and scraper. The upstream feeder comprises a plurality of rollers bearing radially upstream of the scraper against the unscraped workpiece, and the downstream feeder can comprise another such array of rollers or slide blocks bearing radially against the scraped workpiece downstream of the scraper. The feeder has a plurality of jaws or rollers that are normally located downstream of the downstream guide and that pull the rod through the machine. The scraper itself comprises at least one scraping tool that is orbited about the axis between the two guides so as to cut an outer layer off the rod workpiece.
The guides need to hold the workpiece as steady as possible which is a fairly difficult task as it is moving longitudinally while being engaged forcefully in a radial direction by the tool or tools of the rotary scraper head. In particular the rapidly rotating scraper must not set the workpiece vibrating such that the scraper digs excessively into it. The guides must damp this vibration as much as possible.
The scraper is normally carried at the upstream end of a tube centered on and rotatable about the workpiece axis. A fixed tubular housing projects upstream into the scraper tube. Five downstream guide elements are mounted on the tubular housing at an upstream end thereof and directly engage the workpiece after it leaves the scraper. Such a downstream guide is not rigid enough to prevent the workpiece from vibrating, so that the scraper can dig into and damage it.
It is therefore an object of the present invention to provide an improved downstream guide for a rod-peeling machine.
Another object is the provision of such an improved downstream guide for a rod-peeling machine which overcomes the above-given disadvantages, that is which substantially eliminates vibration in the rod so that the scraper can cut the rod to a perfectly cylindrical shape.
A peeling machine through which a rod workpiece is moved along a workpiece axis has upstream and downstream guides centering the workpiece on the axis and axially flanking a rotary scraper engaging the workpiece and carried on an upstream end of a scraper tube coaxially surrounding the downstream guide and rotatable about the workpiece axis. The downstream guide has a stationary tubular housing extending coaxially in the rotatable scraper tube, a plurality of shafts pivotal in the tubular housing about respective guide axes angularly spaced about the workpiece axis, and respective axially elongated guide bars fixed on the shafts, extending axially therealong generally a full length of the scraper tube, and projecting radially of the guide axes therefrom. Guide elementsxe2x80x94rollers or blocksxe2x80x94carried on the bars are engageable radially of the workpiece axis with the workpiece.
Since the guide bars are not set in cutouts of the tube, but instead are mounted internally and extend a good distance in the inner tubular housing, the structure is very stiff and the workpiece will be held solidly at the center. The tubular housing, which is formed between its ends with a narrow axially extending and radially throughgoing slot so that chips and the like do not collect in it, is itself very rigid. What is more, the guide elements carried on the bars engage the workpiece along almost the full length of the scraper tube so that the workpiece is held carefully on the main axis of the machine for vibration-free scraping. Furthermore, since the guide bars and elements are all mounted on the tubular housing, it is possible to remove the entire downstream guide as a single unit for servicing or replacement.
According to the invention the shafts each have an upstream-tapering upstream end and the tubular housing is formed with complementary downstream-flaring seats receiving the upstream shaft ends. A hydraulic biasing system can press the upstream shaft ends upstream into the respective seats and thereby lock angular positions of the shafts and guide bars relative to the guide axes. More particularly the shafts each have downstream ends journaled in a housing of the machine and formed as pistons. The hydraulic biasing unit includes cylinders on the machine housing in which the pistons are axially slidable and means for pressurizing the cylinders and thereby axially pressing and wedging the shaft upstream ends into the respective seats, much like a collet.